The present application is directed to devices for attaching an elongated member to a vertebral member and, more particularly, to devices that provide for dampened movement of the elongated member.
The spine is divided into a variety of regions including the cervical, thoracic, and lumbar regions. The cervical region includes the top seven vertebral members identified as C1-C7. The thoracic region includes the next twelve vertebral members identified as T1-T12. The lumbar region includes five vertebral members L1-L5. The sacrococcygeal region includes nine fused vertebrae that form the sacrum and the coccyx.
Various conditions may lead to damage of the intervertebral discs and the vertebral members. The damage may result from a variety of causes including a specific event such as trauma, a degenerative condition, a tumor, or infection. Damage to the intervertebral discs and vertebral members can lead to pain, neurological deficit, and/or loss of motion.
Elongated members may provide a stable, rigid column that encourages bones to fuse after spinal-fusion surgery. Further, the members may redirect stresses over a wider area away from a damaged or defective region. Also, the members may restore the spine to its proper alignment. In the various surgical procedures, the members may be attached to the exterior of two or more vertebral members, whether it is at a posterior, anterior, or lateral side of the spine.
Proximal Junctional Kyphosis (hereinafter PJK) is a hyperkyphosis of the vertebral segment immediately proximal to a spinal construct. PJK occurs in long spinal constructs, and there are multiple factors that have been hypothesized to play a role in its development. A weakening of the muscles due to muscle dissection, the disruption of the posterior tension band, hybrid constructs (screw/hook), and pre-existing kyphotic hyperflexion have all been reasoned to play a role. Possible side effects of the condition might include facet dislocation and posterior widening of the disc space. Devices should be designed to reduce and/or eliminate PJK.